Button cell having winding electrode and method for the production thereof

ABSTRACT

A button cell includes a button cell housing with a metal cell cup and a metal cell top. The metal cell cup has a cell cup plane region connected to a cell cup lateral surface region, and the metal cell top has a cell top plane region connected to a cell top lateral surface region. The cell cup plane region extends substantially parallel to the cell top plane region, the cell cup lateral surface region extends substantially parallel to and at least partially overlaps the cell top lateral surface region in an overlap area, an electrically insulating seal is disposed in the overlap area, and the cell cup lateral surface region and the cell top lateral surface region provide a force-fit connection therebetween to form a leaktight closure of the button cell housing. The button cell further includes an electrode winding disposed within the housing.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a divisional of U.S. application Ser. No.17/238,329, filed Apr. 23, 2021, which is a divisional of U.S.application Ser. No. 17/173,222, filed Feb. 11, 2021 (now U.S. Pat. No.11,024,907), which is a divisional of U.S. application Ser. No.15/699,435, filed Sep. 8, 2017 (now U.S. Pat. No. 11,024,904), which isa divisional of U.S. application Ser. No. 13/378,117 filed Dec. 14, 2011(now U.S. Pat. No. 9,799,858), which is a § 371 of InternationalApplication No. PCT/EP2010/058637, with an international filing date ofJun. 18, 2010 (WO 2010/146154 A2, published Dec. 23, 2010), which claimspriority to German Patent Application Nos. DE 10 2009 030 359.6, filedJun. 18, 2009, and DE 10 2009 060 800.1, filed Dec. 31, 2009, all ofwhich applications are hereby incorporated by reference herein.

FIELD

This disclosure relates to button cells having a housing consisting oftwo metal housing halves, which contains a wound electrode separatorassembly, and to a method for its production.

BACKGROUND

Button cells conventionally comprise a housing consisting of two housinghalves: a cell cup and a cell top. These may, for example, be producedas stamped parts from nickel-plated deep-drawn sheet metal. Usually, thecell cup is positively poled and the housing top negatively poled. Thehousing may contain a very wide variety of electrochemical systems, forexample, zinc/MnO₂, primary and secondary lithium systems, or secondarysystems such as nickel/cadmium or nickel/metal hydride.

The liquid-tight closure of button cells is conventionally carried outby crimping the edge of the cell cup over the edge of the cell top, incombination with a plastic ring which is arranged between the cell cupand the cell top and is used simultaneously as a sealing element and forelectrical insulation of the cell cup and the cell top. Such buttoncells are described, for example, in DE 31 13 309.

As an alternative, however, it is also possible to manufacture buttoncells in which the cell cup and the cell top are held together in theaxial direction exclusively by a force-fit connection, and whichcorrespondingly do not have a crimped cup edge. Such button cells and amethod for their production are described in DE 10 2009 017 514.8.Regardless of the various advantages which such button cells withoutcrimping may present, they nevertheless cannot withstand such highstresses in the axial direction as comparable button cells with acrimped cup edge, especially as regards axial mechanical loads whichoriginate from inside the button cell. For example, the electrodes ofrechargeable lithium ion systems are constantly subjected to volumechanges during charging and discharging processes. In button cellswithout crimping, the axial forces occurring in this case can naturallycause leaks more easily compared with button cells with crimping.

A solution to this problem may be found in DE 10 2009 030 359.6 and DE10 2009 008 859.8. Inter alia, references may be found therein to buttoncells comprising a housing having a plane bottom region and a plane topregion parallel thereto, an assembly consisting of flat electrode layersand separator layers in the form of a preferably spiral-shaped electrodewinding being arranged in the housing in such a way that the end sidesof the winding face in the direction of the plane bottom region and theplane top region. The electrode layers of the winding are thus orientedessentially orthogonally to the plane bottom and top regions of thehousing. As a result, radial forces such as occur during theaforementioned charging and discharging processes of lithium ion systemscan in principle be absorbed better than in of conventional lithium ionbutton cells, in which electrode layers are arranged stacked in parallelalignment with the plane bottom and top regions.

Windings consisting of flat electrode layers and separator layers can beproduced quite straightforwardly using known methods (see, for example,DE 36 38 793) by the electrodes being applied, in particular laminated,particularly in the form of strips, flat onto a separator provided as anendless band. The assembly consisting of the electrodes and separatorsis generally wound on a so-called “winding mandrel.” After the windinghas been removed from the winding mandrel, an axial cavity is left atthe center of the winding, the effect of which is that the winding maypossibly expand into this cavity. This, however, can sometimes lead toproblems in the electrical contact of the electrodes with the metalhousing halves.

It could therefore be helpful to provide a button cell in which theaforementioned problems do not occur, or only occur to a greatly reducedextent.

SUMMARY

The present invention provides a button cell. The button cell includes abutton cell housing. The button cell housing includes a metal cell cup,the metal cell cup having a cell cup plane region connected to a cellcup lateral surface region, and a metal cell top, the metal cell tophaving a cell top plane region connected to a cell top lateral surfaceregion. The cell cup plane region extends substantially parallel to thecell top plane region, the cell cup lateral surface region extendssubstantially parallel to and at least partially overlaps the cell toplateral surface region in an overlap area, an electrically insulatingseal is disposed between the cell cup lateral surface region and thecell top lateral surface region in the overlap area, and the cell cuplateral surface region and the cell top lateral surface region provide aforce-fit connection therebetween to form a leaktight closure of thebutton cell housing. The button cell further includes an electrodewinding disposed within the housing. The electrode winding has a firstend side, a second end side, and an outer side, the first end side andthe second end side extending substantially parallel to cell cup planeregion and the cell top plane region, the outer side extendingsubstantially perpendicular to the cell cup plane region and the celltop plane region. The electrode winding is formed from a multi-layerassembly that is wound in a spiral shape about an axis. The multi-layerassembly includes a positive electrode formed from a first currentcollector coated with a first electrode material, the first electrodematerial being a lithium intercalating electrode material, a negativeelectrode formed from a second current collector coated with a secondelectrode material, and a separator disposed between the positiveelectrode and the negative electrode. The button cell also includes aconductor including a first portion connected to the first currentcollector or to the second current collector, a second portion, and abend connecting the first portion to the second portion. The firstconductor, including the first portion, second portion, and bendthereof, is a metal foil. In addition, the button cell includes aninsulator positioned between the first conductor and the first end sideof the electrode winding. The second portion of the first conductor atleast partially lies flat between (i) the first end side of theelectrode winding and (ii) a first plane region of the cell cup planeregion and the cell top plane region. The insulator, the second portionof the first conductor, and the first plane region form a sequence ofthree parallel, planar layers in direct contact with one another. Thesecond portion of the first conductor is welded to the first planeregion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B schematically show a cross section of a preferredexample of a button cell 100.

FIGS. 2A to 2C schematically show selected assembly steps of the buttoncell of FIG. 1.

FIGS. 3A and 3B schematically show selected views of windings of thebutton cell.

FIGS. 4A and 4B schematically show two different welds.

FIG. 5 shows microphotographs of a weld from top and cross-sectionalviews.

DETAILED DESCRIPTION

My button cell always comprises two metal housing halves separated fromone another by an electrically insulating seal and forming a housinghaving a plane bottom region and a plane top region parallel thereto. Asmentioned above, the two housing halves are generally a so-called“housing cup” and a “housing top.” In particular, nickel-plated steel orsheet metal are preferred as the material for the housing halves.Trimetals, in particular, are furthermore suitable as the metallicmaterial, for example, ones comprising the sequence nickel, steel (orstainless steel) and copper (in which case the nickel layer preferablyforms the outer side of the button cell housing and the copper layerpreferably forms the inner side).

As the seal, it is, for example, possible to use an injection-moldedseal or a film seal. The latter are described, for example, in DE 196 47593.

At least one positive electrode and at least one negative electrode arearranged inside the housing, specifically each in the form of flatelectrode layers. The electrodes are preferably connected to one anotherby at least one flat separator. The electrodes are preferably laminatedor adhesively bonded onto this separator. The electrodes and theseparator generally each have a thickness only in the μm range. A porousplastic film is generally used as the separator.

This assembly is provided in the form of a winding, particularly in theform of a spiral-shaped winding, in the housing of a button cell, thewinding being arranged such that its end sides face in the direction ofthe plane bottom region and the plane top region of the housing. Fullreference is hereby made to the description of such windings, and buttoncells comprising such windings, in DE 10 2009 030 359.6 and DE 10 2009008 859.8 already mentioned above. All the preferred forms described inthose applications are also intended to apply for the button celldescribed here and the electrode winding described here.

Besides the housing halves and the electrode separator assembly, mybutton cell always also comprises metal conductors which electricallyconnect the at least one positive electrode and/or the at least onenegative electrode respectively to one of the housing halves. Theconductor or conductors connected to the at least one positive electrodepreferably consist of aluminum. The conductors connected to the at leastone negative electrode preferably consist of nickel or copper.

On the electrode side, the conductors are preferably connected tocurrent collectors. The latter are generally metal foils or meshesconventionally coated on both sides with active electrode material.These current collectors preferably consist of aluminum on the side ofthe positive electrode, and preferably nickel or copper on the side ofthe negative electrode. The foils or meshes have, in particular,thicknesses of between 1 μm and 100 μm. The connecting of the conductorsto the current collectors is preferably carried out by welding.

Particularly in respect of preferred forms of the electrode separatorassembly arranged in my button cell, reference is made to DE 10 2009 030359.6 and DE 10 2009 008 859.8. These disclose in particular preferredlayer sequences and layer thicknesses for electrodes and separators, forexample, an assembly comprising the layer sequence:

-   -   negative electrode/separator/positive electrode/separator or    -   positive electrode/separator/negative electrode/separator.

Assemblies comprising the layer sequences:

-   -   negative electrode/separator/positive        electrode/separator/negative electrode or    -   positive electrode/separator/negative        electrode/separator/positive electrode        may also be preferred. The assembly therefore comprises more        than one positive electrode and/or more than one negative        electrode.

Particularly preferably, at least one of the electrodes of a button cellis a lithium intercalation electrode. The button cell is preferably alithium ion battery, in particular a secondary lithium ion battery.

My button cell is distinguished particularly in that at least one of theconductors is welded to the respective housing half, preferably both theconductor connected to the at least one positive electrode and theconductor connected to the at least one negative electrode.

As has already been mentioned above, particularly in lithium ion buttoncells, the electrodes are subject to volume changes during acharging-discharging cycle, as a result of which contact problems mayarise between the conductors and the housing halves. Such contactproblems no longer apply when the conductors are welded to therespective housing halves.

Particularly preferably, the conductor or conductors are welded onto theinner side of the housing in the plane bottom region or the plane topregion, respectively, of the housing. For this purpose, according toconventional methods the welding process must be carried out before thehousing is assembled, which is very difficult to achieve in terms ofproduction technology. Welded connections have therefore been regardedas highly disadvantageous for bonding the conductors to the inner sideof the housing halves. By virtue of my method as described in moredetail below, however, a solution can be provided which also has greatadvantages in terms of production technology.

By the welding, the at least one positive electrode and/or the at leastone negative electrode are thus connected by one or more conductorsdirectly to the plane bottom region or to the plane top region of thehousing of a button cell, the housing top generally being polednegatively and the housing cup positively.

The button cell is preferably a conventional button cell having acircular plane bottom region and a circular plane top region. In somecases, the button cell may nevertheless have an oval configuration. Itis, however, important that the ratio of height to diameter ispreferably always less than 1. Particularly preferably, it is 0.1 to0.9, in particular 0.15 to 0.7. The height is intended to mean theshortest distance between the plane bottom region and the plane topregion parallel thereto. The diameter means the maximum distance betweentwo points on the lateral region of the button cell.

Preferably, the conductors of a button cell are flat conductors, inparticular metal foils, particularly preferably rectangular, strip- orband-shaped metal foils. The foils preferably have thicknesses of 5 μmto 100 μm.

The conductors are preferably separate components bonded, in particularwelded, to the electrodes, in particular to the current collectors inthe electrodes. As an alternative, however, the conductors may also beuncoated sections of a current collector (sections which are free ofactive electrode material), in particular the uncoated ends of such acurrent collector. By bending these uncoated sections, in particularthese uncoated ends, for example, through 90°, these ends can beconnected to the bottom or top region of a button cell. There, theconnecting is preferably carried out by welding.

Preferably, at least one subsection of the conductor or conductors bearsflat on the inner side of the housing half or halves in the bottomand/or top region of the housing, in particular when the conductors areflat conductors such as foils. Such conductors may form a flat layerbetween the inner side of the housing halves and an end side of theelectrode winding, and therefore a large-area electrical contact withthe housing.

Since in principle both positive and negative electrodes may be exposedon the end sides of the electrode winding, however, it is necessary toavoid a short circuit between the electrodes. Particularly preferably,my button cell therefore comprises at least one separate insulatingmeans which prevents direct electrical contact between the end sides ofthe winding and the conductors, in particular a subsection of theconductor or conductors which bears flat on the inner side of thehousing halves. Such an insulating means may, for example, be a film,for example, a plastic adhesive film, by which the side of the conductoror conductors remote from the inner side of the button cell housing iscovered.

The electrode winding of a button cell may be produced by known methods,for example, the method described in DE 36 38 793, according to whichelectrodes and separators are wound on a winding mandrel. After thewinding has been removed from the winding mandrel, there may be an axialcavity at the center of the winding, preferably an essentiallycylindrical axial cavity. In the housing of my button cell, such acavity is delimited laterally by the winding and on the end sides by thebottom or top region of the housing, respectively, or at least by asubregion thereof. Particularly preferably, the at least one conductoris welded to one housing half or the housing halves in one of thesesubregions.

The axial cavity may optionally contain a winding core, which canprevent the winding from expanding uncontrolledly into the cavity.

The button cell is in particular a button cell without crimping, as isdescribed in DE 10 2009 017 514.8. Accordingly, there is preferably anexclusively force-fit connection between the housing halves. The buttoncell thus does not have a crimped cup edge, as is always the case withbutton cells known from the prior art. The button cell is closed withoutcrimping. The content of DE 10 2009 017 514.8 is also fully incorporatedherein by reference. All the preferred forms described in thatapplication is also intended to apply for the button cell described hereand its housing.

As already mentioned above, welding of conductors to the inner side ofbutton cell housings is very elaborate in terms of productiontechnology. I overcome this problem with my method of producing buttoncells, which always comprises at least the following steps:

-   -   (a) providing a first and a second metal housing half        (preferably a cell cup, and a cell top),    -   (b) placing an electrode separator assembly comprising a        positive electrode and a negative electrode in one of the        housing halves (preferably into the cell top), a metal conductor        being bonded to at least one of the electrodes (preferably to        all the electrodes),    -   (c) assembling the two housing halves (preferably by inserting        the cell top into the cell cup), optionally with the provision        of separate steps for sealing the housing (for example, fitting        a seal) and    -   (d) welding at least one of the conductors to the inner side of        one of the metal housing halves.

The components used in the method such as the housing halves, theconductors and the electrode separator assembly, have already beendescribed above. Reference is hereby made to the corresponding remarks.

The method is distinguished in particular in that step (d) is carriedout after step (c). This means that the at least one conductor is weldedto the inner side of the housing when the housing is closed. The weldingmust correspondingly be carried out from the outside through the housingwall of one or both housing halves.

Accordingly, I provide button cells which have weld beads and/or weldspots that pass through the housing, in particular starting from itsouter side.

Particularly preferably, the conductor or conductors and the button cellhousing are connected to one another by one or more spot-like and/orlinear welded connections.

Welding the conductors and the housing is preferably carried out by alaser. Its operating parameters must be adapted as accurately aspossible to the thickness of the housing. The power may, for example, bemodulated by varying the pulse frequency. Lastly, the laser shouldmerely ensure welding of the housing and conductors while othercomponents such as the electrode winding should as far as possible notbe damaged.

Suitable lasers are, for example, commercially available fiber lasers,i.e., solid-state lasers, in which the doped core of a glass fiber formsthe active medium. The most common dopant for the laser-active fibercore is erbium. For high-power applications as in the present case,however, ytterbium and neodymium are more preferred.

Irrespective of the fact that such lasers can be adapted very finely tothe respective housing thickness and conductor dimension, it isnevertheless possible that in certain cases the intensity of the laserwill be selected to be too strong and the laser will penetrate throughthe housing wall and the conductor. For this reason, welding theconductors to the housing is particularly preferably carried out in thesubregion of the bottom or top region, which delimits the axial cavityat the center of the winding on the end side. If a laser beam penetratesthrough the housing in this region, the winding cannot be damaged.Instead, the laser beam will be absorbed by the housing half lyingopposite or by a winding core optionally arranged inside the cavity.

If possible, the conductors to be welded should bear as flatly aspossible on the inner side of the housing. This may, for example, beensured by fixing the conductors flat by an adhesive tape onto or at theend sides of an electrode winding, before the latter is inserted intothe housing.

The aforementioned advantages, and further advantages thereof, are inparticular also revealed by the description which now follows of thedrawings. In this context, the individual features may be implementedseparately or in combination with one another. The examples describedmerely serve for explanation and better understanding, and are in no wayto be interpreted as restrictive.

Button cell 100 comprises two metal housing halves: a metal cup part 101and a metal top part 102. With a seal 103 lying between them, the twoparts are connected together in a leaktight fashion. Together, they forma housing having a plane bottom region 104 and a plane top region 105parallel thereto. In the functional state, these two plane regions 104and 105 form the poles of the button cell 100, from which current can bedrawn by a load. The cell top 102 is inserted into the cell cup 101 sothat the lateral surface regions of the cell top and the cell cupoverlap, the internal radius of the cell cup 101 in the overlap region106 being essentially constant in the direction of the rim 107. The edgeof the cell 101 is thus not crimped. The button cell 100 is therefore anuncrimped button cell.

An assembly 108 of strip-shaped electrodes and strip-shaped separatorsis arranged inside the electrode. The assembly 108 is provided in theform of a spiral-shaped winding, the end sides of which face in thedirection of the plane bottom region 104 and the plane top region 105parallel thereto. The assembly is wound on the winding core 109 at thecenter of the button cell 100. The winding core is a hollow plasticcylinder, which partially fills an axial cavity at the center of thewinding. The cavity itself is delimited laterally by the winding andupward and downward by corresponding circular sections of the plane cupand top regions of the button cell housing. Metal foils 110 and 111,which act as conductors and are connected to the electrodes, bear flaton these regions. These conductors are shielded from the end sides ofthe winding by the insulating elements 112 and 113. The latter are thinplastic films. The wall thickness of the housing in the region of theplane bottom or top region is generally 30 μm to 400 μm. The thicknessof the metal foils 110 and 111 acting as conductors generally lies 5 μmto 100 μm.

Welding of the metal foils 110 and 111, acting as conductors, to therespective housing half, which is preferably done by the schematicallyrepresented laser 114, is preferably carried out in that subregion ofthe bottom region or of the top region of the button cell housing whichdelimits the axial cavity at the center of the winding on the end side.This creates a weld bead 115 which passes fully through the housing ofthe button cell 100 from the outside inward, and by which the internallylying metal foils 110 and 111 acting as conductors are firmly connectedto the inner side of the housing. This can be seen clearly in the detailenlargement (FIG. 1B).

FIG. 2A to FIG. 2C represent some important steps in the production ofan electrode winding, which is suitable in particular for button cells(for example, as represented in FIG. 1). Thus, FIG. 2A shows segmentedcollector foils 201 and 202 coated with active electrode material, towhich conductor strips 203 and 204 offset at an angle of 90° areattached by welding. The conductor 204 on the anode side consists ofnickel or copper, and the conductor 203 on the cathode side of aluminum.The conductors 203 and 204 are respectively applied in a material-freeregion (205, 206) of the collector foils 201 and 202. Elsewhere, theyare coated with active material on both sides. The connection betweenthe collector foils 201 and 202 and the conductors may, for example, beproduced by welding in the region 211.

FIG. 2B and FIG. 2C represent the way in which the rear sides of theconductors 203 and 204 are adhesively bonded using an insulating tape207 and 208 (for example, made of KAPTON or polypropylene) (Step 2).This insulating tape is subsequently intended to function as aninsulating element, which is meant to prevent direct electrical contactbetween the conductors 203 and 204 and the end sides of the electrodewinding which is to be produced. The conductors 203 and 204 are fixed onthe front in a further step (Step 3) with further adhesive strips 209and 210. The region 211 is bonded over in this case.

The conductor position in a winding of electrode foils obtainedaccording to FIG. 2A to FIG. 2C can be seen clearly in FIG. 3A. Twodifferent perspective representations of the same winding are shown(left and right). The conductor 301 (which corresponds to the conductor204 in FIG. 2) and the conductor 302 (which corresponds to the conductor203 in FIG. 2) are themselves aligned axially at a 90° angle to thewinding direction and by folding down by 90° bear flat on the end sides303 and 304 of the electrode winding. The insulating elements 305 and306 (which correspond to the insulating tapes 207 and 208 in FIG. 2)prevent direct electrical contact between the conductors 301 and 302 andthe end sides 303 and 304 of the electrode winding represented. Theouter side of the winding is protected by the insulating film 307.Ideally, the conductors 301 and 302 overlap with the openings of theaxial cavity 308 on the end sides so that welding to the button cellhousing can be carried out in this region. This can be seen clearly inFIG. 3B, as can the winding core 309 which fills the axial cavity 308.

FIGS. 4A and 4B show possible welding variants. For example, it ispossible to configure the weld bead as a minus sign 401 or a plus sign402 (see the respective enlarged representations on the right) so as toindicate the polarity of the respective housing half at the same time.The plus sign 402 is preferably applied on the lower side 404 of abutton cell, and the minus sign on the upper side 403.

FIG. 5 shows an enlarged representation of a cross section through ahousing half 500 of a button cell. The stainless steel cup wall 501, thealuminum conductor 502 bearing flat underneath and an insulating tape503 of KAPTON film arranged below can be seen. The weld beads 504 and505, which extend from the outer side of the housing inward as far asthe insulating tape 503 of KAPTON film can be seen clearly. The top leftimage is a plan view of the cutaway plane bottom region of the housinghalf 500. The housing half 500 and the conductor 502 have been weldedusing an ytterbium-doped fiber laser of the YLR-400-AC type(manufacturing company IPG Photonics Corporation, USA). The intensity ofthe laser was in this case adjusted so that the insulating tape 503 wasnot penetrated.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive. Itwill be understood that changes and modifications may be made by thoseof ordinary skill within the scope of the following claims. Inparticular, the present invention covers further embodiments with anycombination of features from different embodiments described above andbelow. Additionally, statements made herein characterizing the inventionrefer to an embodiment of the invention and not necessarily allembodiments.

The terms used in the claims should be construed to have the broadestreasonable interpretation consistent with the foregoing description. Forexample, the use of the article “a” or “the” in introducing an elementshould not be interpreted as being exclusive of a plurality of elements.Likewise, the recitation of “or” should be interpreted as beinginclusive, such that the recitation of “A or B” is not exclusive of “Aand B,” unless it is clear from the context or the foregoing descriptionthat only one of A and B is intended. Further, the recitation of “atleast one of A, B and C” should be interpreted as one or more of a groupof elements consisting of A, B and C, and should not be interpreted asrequiring at least one of each of the listed elements A, B and C,regardless of whether A, B and C are related as categories or otherwise.Moreover, the recitation of “A, B and/or C” or “at least one of A, B orC” should be interpreted as including any singular entity from thelisted elements, e.g., A, any subset from the listed elements, e.g., Aand B, or the entire list of elements A, B and C.

What is claimed is:
 1. A button cell, comprising: a button cell housing,the button cell housing including: a metal cell cup, the metal cell cuphaving a cell cup plane region connected to a cell cup lateral surfaceregion, and a metal cell top, the metal cell top having a cell top planeregion connected to a cell top lateral surface region, wherein the cellcup plane region extends substantially parallel to the cell top planeregion, the cell cup lateral surface region extends substantiallyparallel to and at least partially overlaps the cell top lateral surfaceregion in an overlap area, an electrically insulating seal is disposedbetween the cell cup lateral surface region and the cell top lateralsurface region in the overlap area, and the cell cup lateral surfaceregion and the cell top lateral surface region provide a force-fitconnection therebetween to form a leaktight closure of the button cellhousing; an electrode winding disposed within the housing, the electrodewinding having a first end side, a second end side, and an outer side,the first end side and the second end side extending substantiallyparallel to cell cup plane region and the cell top plane region, theouter side extending substantially perpendicular to the cell cup planeregion and the cell top plane region, the electrode winding being formedfrom a multi-layer assembly that is wound in a spiral shape about anaxis, the multi-layer assembly including: a positive electrode formedfrom a first current collector coated with a first electrode material,the first electrode material being a lithium intercalating electrodematerial, a negative electrode formed from a second current collectorcoated with a second electrode material, and a separator disposedbetween the positive electrode and the negative electrode; a firstconductor including a first portion connected to the first currentcollector or to the second current collector, a second portion, and abend connecting the first portion to the second portion, wherein thefirst conductor, including the first portion, second portion, and bendthereof, is a metal foil; and an insulator positioned between the firstconductor and the first end side of the electrode winding, wherein thesecond portion of the first conductor at least partially lies flatbetween (i) the first end side of the electrode winding and (ii) a firstplane region of the cell cup plane region and the cell top plane region,wherein the insulator, the second portion of the first conductor, andthe first plane region form a sequence of three parallel, planar layersin direct, two-dimensional contact with one another, and wherein thesecond portion of the first conductor is welded to the first planeregion.
 2. The button cell as claimed in claim 1, wherein the secondportion of the first conductor is welded to the first plane region viaat least one weld bead and/or weld spot that originates from an outerside of the button cell housing.
 3. The button cell as claimed in claim2, wherein the at least one weld bead and/or weld spot is at least onelaser weld bead and/or laser weld spot.
 4. The button cell as claimed inclaim 2, wherein the electrode winding includes an open cavity extendingalong the axis, the open cavity having a first end and a second endextending substantially parallel to cell cup plane region and the celltop plane region, wherein the second portion of the first conductor iswelded to the first plane region in an area that corresponds to the opencavity.
 5. The button cell as claimed in claim 1, wherein the firstportion of the first conductor is connected to the first currentcollector, the button cell further comprising: a second conductorincluding a first portion connected to the second current collector, asecond portion, and a bend connecting the first portion to the secondportion, wherein the second conductor, including the first portion,second portion, and bend thereof, is a metal foil; and a secondinsulator positioned between the second conductor and the second endside of the electrode winding.
 6. The button cell as claimed in claim 5,wherein the second portion of the second conductor at least partiallylies flat between (i) the second end side of the electrode winding and(ii) a second plane region of the cell cup plane region and the cell topplane region, wherein the second insulator, the second portion of thesecond conductor, and the second plane region form a sequence of threeparallel, planar layers in direct contact with one another, and whereinthe second portion of the second conductor is welded to the second planeregion.
 7. The button cell as claimed in claim 6, wherein the secondportion of the first conductor is welded to the first plane region viaat least one first weld bead and/or weld spot that originates from anouter side of the button cell housing, and wherein the second portion ofthe second conductor is welded to the second plane region via at leastone second weld bead and/or weld spot that originates from an outer sideof the button cell housing.
 8. The button cell as claimed in claim 7,wherein the at least one first weld bead and/or weld spot is a laserweld bead and/or laser weld spot, and wherein the at least one secondweld bead and/or weld spot is a second laser weld bead and/or laser weldspot.
 9. The button cell as claimed in claim 7, wherein the electrodewinding includes an open cavity extending along the axis, the opencavity having a first end and a second end extending substantiallyparallel to cell cup plane region and the cell top plane region, whereinthe second portion of the first conductor is welded to the first planeregion in an area of the first plane region that corresponds to the opencavity, and wherein the second portion of the second conductor is weldedto the second plane region in an area of the second plane region thatcorresponds to the open cavity.
 10. The button cell as claimed in claim1, wherein the first conductor is welded to the first current collector.11. The button cell as claimed in claim 1, wherein the insulator is athin plastic film, further comprising an insulating tape adhesivelybonded to the first conductor.
 12. The button cell as claimed in claim1, wherein the first current collector is a first metallic foil or meshcomprising aluminum, wherein the second current collector is a secondmetallic foil or mesh comprising copper and/or nickel, and wherein thefirst metallic foil or mesh and the second metallic foil or mesh bothhave a thickness in the range of 1 μm to 100 μm.
 13. The button cell asclaimed in claim 1, wherein the electrode winding is cylindrical,wherein the second portion of the first conductor forms a rectangularfirst flat layer lying between the first end side of the electrodewinding and the first plane region, and wherein the rectangular firstflat layer has a length that is less than a diameter of the first endside of the electrode winding.
 14. The button cell as claimed in claim1, wherein the first portion of the first conductor is connected to afirst portion of the first current collector located a peripheral regionof the electrode winding, and wherein the bend of the first conductor isa 90° bend oriented such that the second portion of the first conductoris located radially inward from the first portion of the firstconductor.
 15. The button cell as claimed in claim 14, wherein the firstportion of the first current collector is an uncoated section that isfree of the first electrode material, and wherein the first portion ofthe first conductor is connected to the first portion of the firstcurrent collector by welding.
 16. A button cell, comprising: a buttoncell housing, the button cell housing including: a metal cell cup, themetal cell cup having a cell cup plane region connected to a cell cuplateral surface region, and a metal cell top, the metal cell top havinga cell top plane region connected to a cell top lateral surface region,wherein the cell cup plane region extends substantially parallel to thecell top plane region, the cell cup lateral surface region extendssubstantially parallel to and at least partially overlaps the cell toplateral surface region in an overlap area, an electrically insulatingseal is disposed between the cell cup lateral surface region and thecell top lateral surface region in the overlap area, and the cell cuplateral surface region and the cell top lateral surface region provide aforce-fit connection therebetween to form a leaktight closure of thebutton cell housing; an electrode winding disposed within the housing,the electrode winding having a first end side, a second end side, and anouter side, the first end side and the second end side extendingsubstantially parallel to cell cup plane region and the cell top planeregion, the outer side extending substantially perpendicular to the cellcup plane region and the cell top plane region, the electrode windingbeing formed from a multi-layer assembly that is wound in a spiral shapeabout an axis, the multi-layer assembly including: a positive electrodeformed from a first current collector coated with a first electrodematerial, the first electrode material being a lithium intercalatingelectrode material, a negative electrode formed from a second currentcollector coated with a second electrode material, and a separatordisposed between the positive electrode and the negative electrode, afirst end section of the first current collector, the first end sectionof the first current collector being bent so as to extend out of theelectrode winding, an insulator positioned between the first end side ofthe electrode winding and the first portion of the first end section ofthe first current collector, wherein the first portion of the first endsection of the first current collector at least partially lies between(i) the first end side of the electrode winding and (ii) a first planeregion of the cell cup plane region and the cell top plane region,wherein the first current collector, including the first end sectionthereof, is a first metallic foil or mesh, wherein the insulator, thefirst portion of the first end section of the first current collector,and the first plane region form a sequence of three parallel, planarlayers in direct contact with one another, and wherein the first portionof the first end section of the first current collector is welded to thefirst plane region.
 17. The button cell as claimed in claim 16, whereinthe first portion of the first end section of the first currentcollector is welded to the first plane region via at least one weld beadand/or weld spot that originates from an outer side of the button cellhousing.
 18. The button cell as claimed in claim 17, wherein the atleast one weld bead and/or weld spot is at least one laser weld beadand/or laser weld spot.
 19. The button cell as claimed in claim 17,wherein the electrode winding includes an open cavity extending alongthe axis, the open cavity having a first end and a second end extendingsubstantially parallel to cell cup plane region and the cell top planeregion, wherein first portion of the first end section of the firstcurrent collector is welded to the first plane region in an area thatcorresponds to the open cavity.
 20. The button cell as claimed in claim16, the button cell further comprising: a first end section of thesecond current collector, the first end section of the second currentcollector being bent so as to extend out of the electrode winding, and asecond insulator positioned between the first end section of the secondcurrent collector and the second end side of the electrode winding,wherein the second current collector, including the first end sectionthereof, is a second metallic foil or mesh.
 21. The button cell asclaimed in claim 20, wherein the first end section of the second currentcollector at least partially lies flat between (i) the second end sideof the electrode winding and (ii) a second plane region of the cell cupplane region and the cell top plane region, wherein the secondinsulator, the first end section of the second current collector, andthe second plane region form a sequence of three parallel, planar layersin direct contact with one another, and wherein the first end section ofthe second current collector is welded to the second plane region. 22.The button cell as claimed in claim 21, wherein the first end section ofthe first current collector is welded to the first plane region via atleast one first weld bead and/or weld spot that originates from an outerside of the button cell housing, and wherein first end section of thesecond current collector is welded to the second plane region via atleast one second weld bead and/or weld spot that originates from anouter side of the button cell housing.
 23. The button cell as claimed inclaim 22, wherein the at least one first weld bead and/or weld spot is alaser weld bead and/or laser weld spot, and wherein the at least onesecond weld bead and/or weld spot is a second laser weld bead and/orlaser weld spot.
 24. The button cell as claimed in claim 22, wherein theelectrode winding includes an open cavity extending along the axis, theopen cavity having a first end and a second end extending substantiallyparallel to cell cup plane region and the cell top plane region, whereinthe first end section of the first current collector is welded to thefirst plane region in an area of the first plane region that correspondsto the open cavity, and wherein the first end section of the secondcurrent collector is welded to the second plane region in an area of thesecond plane region that corresponds to the open cavity.
 25. The buttoncell as claimed in claim 20, wherein the insulator is a first thinplastic film and the second insulator is a second thin plastic film,further comprising an insulating tape adhesively bonded to the first endsection of the first current collector and a second insulating tapeadhesively bonded to the first end section of the second currentcollector.
 26. The button cell as claimed in claim 20, wherein the firstcurrent collector is bent such that the first end section of the firstcurrent collector that extends out of the electrode winding is locatedradially inward from a bend, of the first current collector, disposed inthe winding, and wherein the second current collector is bent such thatthe first end section of the second current collector that extends outof the electrode winding is located radially inward from a bend, of thesecond current collector, disposed in the winding.
 27. The button cellas claimed in claim 16, wherein the insulator is a thin plastic film,further comprising an insulating tape adhesively bonded to the first endsection of the first current collector.
 28. The button cell as claimedin claim 16, wherein the first current collector is a first metallicfoil or mesh comprising aluminum, wherein the second current collectoris a second metallic foil or mesh comprising copper and/or nickel, andwherein the first metallic foil or mesh and the second metallic foil ormesh both have a thickness in the range of 1 μm to 100 μm.
 29. Thebutton cell as claimed in claim 16, wherein the electrode winding iscylindrical, wherein at least a portion of the first end section of thefirst current collector forms a rectangular first strip.
 30. The buttoncell as claimed in claim 16, wherein the first current collector is bentsuch that the first end section of the first current collector thatextends out of the electrode winding is located radially inward from abend, of the first current collector, disposed in the winding.